The present invention relates to a magnetic head for magnetically recording and reproducing signals in perpendicular magnetization.
Conventional magnetic recording employs a ring-type magnetic recording head for magnetizing a magnetic recording medium in the longitudinal direction thereof to produce a remanence parallel to the magnetic coating in the magnetic recording medium. With this recording process, if the signal packing density becomes higher, then the demagnetizing field produced in the magnetic recording medium is increased, causing attenuation and rotation of the remanence. The recorded signals then become difficult to detect.
To eliminate the above drawback with the prior longitudinal magnetic recording process, there has been proposed a perpendicular magnetization process for magnetizing the magnetic layer of the magnetic recording medium perpendicularly to the direction of travel of the magnetic recording medium. The perpendicular magnetization is advantageous in that as the signal packing density is increased, the demagnetizing field is reduced while the remanence is not reduced, from the standpoint of a theoretical analysis. This magnetization mode is thus capable of good recording and reproducing characteristics in high signal packing densities.
Known magnetic recording mediums used for perpendicular magnetization are made of a magnetic material, such as cobalt, chromium, and the like, having perpendicular magnetization anisotropy. Various magnetic heads are known for perpendicular magnetization.
One conventional magnetic head for perpendicular magnetization has a coil wound around a core for generating a recording magnetic field across and through a magnetic recording medium between the core and a main magnetic pole having a reduced thickness. This known magnetic head has an open magnetic path and hence suffers a poor efficiency as a playback head.
Another type of magnetic head for perpendicular magnetization includes a coil wound around a substantially C-shaped core including two arms having distal ends which have different surfaces areas and against which slides a magnetic recording medium composed of a magnetic recording layer and a thin film of high magnetic permeability below the magnetic recording layer. In operation, the magnetic head creates a closed magnetic path passing therethrough and through the thin film beneath the magnetic recording layer. The magnetic head of this type does not have the problem with the other prior head, but fails to magnetize the magnetic recording layer since there are limitations on efforts to reduce the surface areas of the distal ends of the arms of the core.